The subject invention concerns a device for setting the relative positions of pivotable elements, such as setting the position of inclination of the back rest of a seat, preferably a vehicle seat, comprising pivot components disposed in pairs for mutual rotational movement and arranged to be associated for instance with the back rest and with the seat cushion part, respectively of the seat, each component of said pair being formed with at least one of concentric side by side ring gears and with a number of planetary wheel gears spaced about the associated ring gear circumference with each such planetary gear wheel simultaneously engaging the two ring gears, said planetary gear wheels and said ring gears being mutually adapted to cause the ring gears and the associated rotational components to perform a relative angular movement upon rolling of the planetary gear wheels in mesh with the ring gears.
In devices of the kind defined above it is often of very great importance that the components of the joint be kept together in a very stable manner, without play or free slack.
The main purpose of the invention is to provide a device of this kind, in which the pivot components of the joint are efficiently kept together in such a manner that no play occurs.
This purpose is achieved by means of a device in accordance with the invention, in which the planetary gear wheels are supported so as to move radially and in which means are provided to urge the planetary gear wheels radially outward into contact with the ring gears.
Preferably, the planetary gear wheels are spring biased in the direction towards the ring gears.
In addition, the planetary gear wheels preferably are interconnected by means of planetary gear carriers of a resilient material. In accordance with one preferred embodiment of the invention the planetary gear carriers are shaped as annular members formed with planetary gear wheel bearing means spaced around the periphery of the annular member.
In addition, the planetary gear wheel shaft bearing means preferably are formed by the cooperation between peripheral grooves formed in the planetary gear wheel shafts and edge portions of the planetary gear carriers in engagement with said grooves.
Preferably, the planetary wheel gear carriers are each formed by an essentially circular ring-shaped spring member, the periphery of which is biased into nesting engagement with said grooves formed in the end portions of the planet wheel bearing shafts, thus forming a race cooperating with the bottom faces of the shaft grooves.
In addition, means preferably are provided to at least partially counteract, i.e. annul the contact pressure exerted on the planetary gear wheels during setting, i.e. during the pivotal movement of the pivot components.
Furthermore, the means arranged to counteract the contact pressure preferably could be operatively connected with the actuating means designed to set the positions of the pivot components for the purpose of diverting the actuating force in a direction acting oppositely to the contact pressure.
The pivot components or components of the articulated or pivotable joint preferably are plates arranged in abutting relationship, each one having two concentric apertures the periphery of which forms the associated gear ring, the two plates being retained one against the other by means of abutment against its associated one of external flat faces and kept together with spacer members positioned between the planetary gear wheels and bridging the thickness of the fittings.
Preferably, the spacer members are formed with external faces in abutment against the ring gear tooth apices and forming sliding tracks on which slide said apices for the purpose of maintaining the concentric relationship of the gear tracks.